The suspect arrested in the Bethesda Row Lululemon Athletica slaying was the victim's coworker, who had claimed to be a victim herself, NBC Washington's Pat Collins reported.

Brittany Norwood was found bound and injured but alive at the bloody scene when a third coworker opened the athletics store and found 30-year-old Jayna Murray's body Saturday morning. Montgomery County, Md., police arrested Norwood Friday afternoon when she went to police headquarters for her third or fourth interview in the investigation. They charged Norwood with first-degree murder.

Woman Arrested in Bethesda Row Murder

"I can assure you that the people of Bethesda are breathing easier tonight than they were earlier today," said Montgomery County Vice President Roger Berliner, who represents Bethesda. "There was a great deal of fear engendered by this crime."

"I am delighted that we have been able to move so fast," Montgomery County Executive Isiah Leggett said.

Lululemon Murder Arrest

Investigators had been going over the story the suspect told while in the hospital. She told police that she and Murray closed the store at 9 p.m. Friday and left at about 9:45 p.m., police said. She said she realized that she had left her wallet in the store but did not have the keys to re-enter, so she called Murray and they arranged to meet back at the store. As they went back in at about 10:05 p.m., two masked men dressed in black also entered, Norwood told police.

Police believe that timeline but said there is no forensic nor physical evidence supporting her story that two men attacked Murray and herself, Montgomery County Police Chief Thomas Manger said. Nor is there evidence supporting Norwood's claim that she and Murray were sexually assaulted. Police also said there is no evidence Norwood was bound by someone else.

RAW VIDEO: Lululemon Slaying Arrest News Conference

"All we had was what what we believed was a surviving victim told us, and you have to take victims, especially victims of sexual assault, you have to take their story as truthful," Manger said. "You have to work under that assumption. As the investigation went on, we went where the evidence led us to go."

Police could not say whether the return to the store was planned with an attack in mind.

In addition to interviewing Norwood three or four times, investigators reviewed surveillance video and collected forensic evidence at the scene. Investigators found no eyewitnesses, and surveillance video showed no suspects.

Evidence found in Murray's car led police to develop Norwood as a suspect. Police believe she moved the car three blocks away from the scene to a parking lot in Bethesda, where it was found.

Tracks found in the store had been made by a pair of size 14 shoes found in the store, Manger said.

Murray and Norwood had been involved in some sort of dispute -- witnesses heard two women arguing -- but police do not know the nature of the argument, Manger said.

Police did not say how Murray was killed or what weapon may have been used and said further evidence is being held for trial.

Norwood is scheduled to appear in court Monday.

Police had received at least 57 tips in the investigation this week, and the reward had reached almost $160,000, Collins reported.

Friends, family and the Bethesda business community planned a remembrance of Murray for Friday evening. They planned to meet at the Mindfulness Center at 4963 Elm St. in Bethesda and walk to the store.

Vigils also were planned at the Lululemon stores in Los Angeles and Walnut Creek, Calif. Friends of Murray planned a vigil in Union Square, N.Y.

Reading a statement from Lululemon, Kenny Fried said the three Lululemon stores in the area will remain closed through Saturday. The Bethesda store is closed indefinitely. He had no comment about Norwood.